LXR linux/arch/arm64/include/asm/pointer

   1// SPDX-License-Identifier: GPL-2.0
   2#ifndef __ASM_POINTER_AUTH_H
   3#define __ASM_POINTER_AUTH_H
   4
   5#include <linux/bitops.h>
   6#include <linux/random.h>
   7
   8#include <asm/cpufeature.h>
   9#include <asm/memory.h>
  10#include <asm/sysreg.h>
  11
  12#ifdef CONFIG_ARM64_PTR_AUTH
  13/*
  14 * Each key is a 128-bit quantity which is split across a pair of 64-bit
  15 * registers (Lo and Hi).
  16 */
  17struct ptrauth_key {
  18        unsigned long lo, hi;
  19};
  20
  21/*
  22 * We give each process its own keys, which are shared by all threads. The keys
  23 * are inherited upon fork(), and reinitialised upon exec*().
  24 */
  25struct ptrauth_keys {
  26        struct ptrauth_key apia;
  27        struct ptrauth_key apib;
  28        struct ptrauth_key apda;
  29        struct ptrauth_key apdb;
  30        struct ptrauth_key apga;
  31};
  32
  33static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
  34{
  35        if (system_supports_address_auth()) {
  36                get_random_bytes(&keys->apia, sizeof(keys->apia));
  37                get_random_bytes(&keys->apib, sizeof(keys->apib));
  38                get_random_bytes(&keys->apda, sizeof(keys->apda));
  39                get_random_bytes(&keys->apdb, sizeof(keys->apdb));
  40        }
  41
  42        if (system_supports_generic_auth())
  43                get_random_bytes(&keys->apga, sizeof(keys->apga));
  44}
  45
  46#define __ptrauth_key_install(k, v)                             \
  47do {                                                            \
  48        struct ptrauth_key __pki_v = (v);                       \
  49        write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);     \
  50        write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);     \
  51} while (0)
  52
  53static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
  54{
  55        if (system_supports_address_auth()) {
  56                __ptrauth_key_install(APIA, keys->apia);
  57                __ptrauth_key_install(APIB, keys->apib);
  58                __ptrauth_key_install(APDA, keys->apda);
  59                __ptrauth_key_install(APDB, keys->apdb);
  60        }
  61
  62        if (system_supports_generic_auth())
  63                __ptrauth_key_install(APGA, keys->apga);
  64}
  65
  66extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
  67
  68/*
  69 * The EL0 pointer bits used by a pointer authentication code.
  70 * This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
  71 */
  72#define ptrauth_user_pac_mask() GENMASK(54, vabits_user)
  73
  74/* Only valid for EL0 TTBR0 instruction pointers */
  75static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
  76{
  77        return ptr & ~ptrauth_user_pac_mask();
  78}
  79
  80#define ptrauth_thread_init_user(tsk)                                   \
  81do {                                                                    \
  82        struct task_struct *__ptiu_tsk = (tsk);                         \
  83        ptrauth_keys_init(&__ptiu_tsk->thread.keys_user);               \
  84        ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user);             \
  85} while (0)
  86
  87#define ptrauth_thread_switch(tsk)      \
  88        ptrauth_keys_switch(&(tsk)->thread.keys_user)
  89
  90#else /* CONFIG_ARM64_PTR_AUTH */
  91#define ptrauth_prctl_reset_keys(tsk, arg)      (-EINVAL)
  92#define ptrauth_strip_insn_pac(lr)      (lr)
  93#define ptrauth_thread_init_user(tsk)
  94#define ptrauth_thread_switch(tsk)
  95#endif /* CONFIG_ARM64_PTR_AUTH */
  96
  97#endif /* __ASM_POINTER_AUTH_H */
  98